When you are fortunate enough to have a backyard swimming pool or spa, you must also accept that they require regular maintenance to keep them clean. Of course, we know that it's important to keep leaves and debris out of the water. But even if you are diligent about keeping the water free of debris, stains or grime can collect on the tiles at the pool's waterline or fill line.
The grime is an accumulation of body soil, sunscreen, and mineral deposits (scale) that cling to the tiles. If you have hard-water deposits or stains in sinks or tubs inside your house, they will probably happen to your pool surfaces as well. As water evaporates, scaling occurs when mineral deposits cling to the sides of a pool. It shows up as white or gray scum and is difficult to remove. The two main types of scaling left on the tiles are calcium deposits:
- Calcium carbonate appears as white, flaky deposits on the tile. If treated with muriatic acid, it will bubble up. Calcium carbonate is the easiest type of deposit to remove.
- Calcium silicate is slightly darker grey, doesn't flake, and doesn't react to muriatic acid. Calcium silicate is much more difficult to remove if it has remained on the tile for a long period.
Pool staining can show up in a variety of colors and occurs as the result of a chemical imbalance in the water reacting with the pool's surfaces. If you have a pool maintenance company, they regularly blast away the build-up as part of their routine cleaning. If you are taking care of the pool yourself, frequent cleaning will prevent the stains from becoming so difficult to remove that you must replace the tiles for a clean look.
How Often to Clean Pool Waterline Tiles
For the easiest maintenance, the waterline tiles should be cleaned as soon as you notice any discoloration—weekly or monthly. Small levels of build-up at the waterline are much easier to clean than waiting until it is heavy. The tiles should always be cleaned at the beginning and end of the pool season.
If the build-up at the waterline is exceptionally heavy with mineral deposits, algae, and dirt, plan to do the removal in increments over several days or weeks. This will prevent your pool's filtering system from becoming overwhelmed and help maintain the chemical balance of the water.
Equipment / Tools
- Pool vacuum
- Skimmer net
- Eye protection
- Stiff-bristled brush
- Soft-bristled brush
- Plastic bucket
- Pumice stone
- Rubber gloves
- Distilled white vinegar
- Cleaning vinegar
- Baking soda
- Dishwashing liquid
- Melamine sponge
- Commercial tile cleaner
When cleaning the waterline tiles, always begin with the most gentle method first. It may take care of the grime without having to progress to more difficult and toxic cleaning methods.
Remove All Organic Matter
If the pool has leaves, grass clippings, or other organic matter in the water, use a pool vacuum or net skimmer to remove as much of the problem as possible.
Drop the Waterline
It is easier to clean the stained tiles if the waterline is slightly below its usual position. You can choose to work from the pool deck or while you are in the water.
Use a Scrub Brush
Use a stiff-bristled scrub brush (no wire bristles) to scrub away the mineral deposits. Work in a circular motion in an area about three or four feet wide. If you have glass tiles, a soft-bristled brush is a better choice to prevent scratching the glass. For tight, small areas, an old toothbrush works well.
Remove Dirt and Grime
Once you have loosened the mineral deposits from the work area, remove the accumulation of body soil, dust, and grime. This can be done by scrubbing the area with one of these solutions that you have mixed in a plastic bucket:
- one part water and one part distilled white vinegar
- two parts water and one part cleaning vinegar
- dry baking soda and a few drops of water to create a paste
- one-fourth cup dishwashing liquid and one gallon of water
Dip the scrub brush in the solution and scour the tiles at the waterline. Use a melamine sponge (Mr. Clean Magic Eraser is a popular one) for tough-to-remove stains. Splash a bit of pool water or fresh water over the freshly cleaned area and repeat the scrubbing and cleaning steps as you move around the perimeter of the pool.
While these cleaning solutions are not toxic, wearing goggles or eye protection is suggested to prevent splatters into the eyes.
Use a Pumice Stone
If the scrub brush and cleaning solutions did not remove the mineral deposits, then it's time to use a pumice stone. These are available online and at home improvement and pool supplies stores. Made of ground volcanic rock, the stone will break apart the deposits. You must keep the stone and tile wet at all times while you work or there will be excessive scratching. Work slowly with a light touch as you scrub in gentle circles along the waterline.
Try a Commercial Cleaner or Professional
If the pumice stone did not remove the build-up, you can try a tile cleaner that contains sulfamic acid (CLR or Lime-Away). These types of cleaners are harsh and must be used with extreme care. They should not be used after you have added the regular pool chemicals to the water. After using, allow several days to pass before you treat the pool water with chemicals or swim in the water.
Rather than working with these cleaners, it might be time to consult with a pool maintenance company that can clean the tile with a high-pressure baking soda blast.